UC Riverside climate researcher Robert Allen says California should get ready for more rain. Unlike other recent work in the field, Allen has just published a study that says rainfall in the state will increase in the coming years if the planet continues to warm at its current pace. Allen, 42, is a professor of earth sciences and has been studying climate issues for two decades. He came to UCR six years ago. His study projects that by 2100, precipitation in California will rise 12 percent. But Southern California rainfall won’t change much.